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Journal ArticleDOI

Using self-organizing maps to investigate environmental factors regulating colony size and breeding success of the White Stork (Ciconia ciconia)

01 Apr 2013-Journal of Ornithology (Springer-Verlag)-Vol. 154, Iss: 2, pp 481-489

TL;DR: The self-organizing map algorithm (SOM) proved a relevant tool to help determine actual dynamics in White Stork colonies, and thus to support effective conservation decisions at a regional scale.

AbstractWe studied variations in the size of breeding colonies and in breeding performance of White Storks Ciconia ciconia in 2006–2008 in north-east Algeria. Each colony site was characterized using 12 environmental variables describing the physical environment, land-cover categories, and human activities, and by three demographic parameters: the number of breeding pairs, the number of pairs with chicks, and the number of fledged chicks per pair. Generalized linear mixed models and the self-organizing map algorithm (SOM, neural network) were used to investigate effects of biotic, abiotic, and anthropogenic factors on demographic parameters and on their relationships. Numbers of breeding pairs and of pairs with chicks were affected by the same environmental factors, mainly anthropogenic, which differed from those affecting the number of fledged chicks per pair. Numbers of fledged chicks per pair was not affected by colony size or by the number of nests with chicks. The categorization of the environmental variables into natural and anthropogenic, in connection with demographic parameters, was relevant to detect factors explaining variation in colony size and breeding parameters. The SOM proved a relevant tool to help determine actual dynamics in White Stork colonies, and thus to support effective conservation decisions at a regional scale.

Topics: Ciconia (56%), White stork (53%)

Summary (1 min read)

Jump to: [Introduction][Methods][Results] and [Discussion]

Introduction

  • Environmental conditions are significant determinants in breeding habitats, and may influence the breeding success of birds and contribute to the variability of breeding populations (Lack 1968).
  • Most demographic studies on this species have been conducted in temperate areas, mainly in Europe, where environmental conditions and life history traits (e.g., clutch size, colonial or solitary nesting) differ from those encountered in northern Africa.

Methods

  • (6) Annual mean of maximum temperatures (°C). (7) Approximate flight distance between the colony and the closest urban area (in m, ±10 m).
  • (12) Type of colony [monospecific for the colonies occupied only by White Storks; plurispecific for the colonies occupied by storks and Cattle Egrets (Ardea ibis)].
  • Secondly, the authors aimed to emphasize the relationships between environmental variables and the three breeding parameters recorded for each colony (the number of breeding pairs ‘‘HPa’’, the number of pairs with chicks ‘‘HPm’’, and the number of fledged chicks ‘‘JZG’’).

Results

  • Breeding parameters and numbers of nests found each year are shown in Table 1.
  • The mean number of fledged chicks per nest varied between years (being higher in 2006 than in other years), but was not affected by the number of pairs in the colony or the number of pairs with chicks (Table 2).
  • The majority of Stork colonies were distributed in the north-eastern part of the wilaya, particularly on the plains of El Madher, Malel, Belezma and Ain Touta.
  • Cluster B and C included colonies located in areas with low inhabitant density, relatively close to urban areas and refuse tips, and intermediate altitude, temperature and precipitation.
  • These areas corresponded to the regions where intense farming uses irrigation.

Discussion

  • The authors results suggest that the largest colonies were established close to urban areas and refuse, and consequently in the most human-populated zones.
  • In their study, the higher number of fledged chicks per nest in colonies situated in areas with relatively high precipitation may reflect an indirect effect of precipitation on food abundance, as suggested by other studies on this species (Denac 2006; Nevoux et al. 2008).
  • The geographical location and the average colony size of these 62 colonies are reported in Fig 1. b Gradient analysis of the value for each habitat variable on the trained SOM represented by a shaded scale (light low value, dark high value).
  • The authors study thus supports the idea that identifying the variables which significantly affect the breeding parameters of White Storks should be a research priority for conservationists and environmental policy makers.

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Using self-organizing maps to investigate environmental
factors regulating colony size and breeding success of the
White Stork (Ciconia ciconia)
Abdelkrim Si Bachir, Haroun Chenchouni, Nawel Djeddou, Christophe
Barbraud, Régis Céréghino, Frédéric Santoul
To cite this version:
Abdelkrim Si Bachir, Haroun Chenchouni, Nawel Djeddou, Christophe Barbraud, Régis Céréghino, et
al.. Using self-organizing maps to investigate environmental factors regulating colony size and breeding
success of the White Stork (Ciconia ciconia). Journal für Ornithologie = Journal of Ornithology,
Springer Verlag, 2013, 154, pp.481-489. �10.1007/s10336-012-0915-2�. �hal-00913174�

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Eprints ID : 10207
To link to this article : doi:10.1007/s10336-012-0915-2
URL : http://dx.doi.org/10.1007/s10336-012-0915-2
To cite this version : Si Bachir, Abdelkrim and Chenchouni, Haroun
and Djeddou, Nawel and Barbraud, Christophe and Céréghino, Régis
and Santoul, Frédéric Using self-organizing maps to investigate
environmental factors regulating colony size and breeding success of
the White Stork (Ciconia ciconia). (2013) Journal of Ornithology, vol.
154 (n° 2). pp. 481-489. ISSN 0021-8375
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Using self-organizing maps to investigate environmental factors
regulating colony size and breeding success of the White Stork
(Ciconia ciconia)
Abdelkrim Si Bachir
Haroun Chenchouni
Nawel Djeddou
Christophe Barbraud
Re
´
gis Ce
´
re
´
ghino
Fre
´
deric Santoul
Abstract We studied variation s in the size of breeding
colonies and in breeding performance of White Storks
Ciconia ciconia in 2006–2008 in north-east Algeria. Each
colony site was characterized using 12 environmental
variables describing the physical environment, land-cover
categories, and human activities, and by three demographic
parameters: the number of breeding pairs, the number of
pairs with chicks, and the number of fledged chicks per
pair. Generalized linear mixed models and the self-orga-
nizing map algorithm (SOM, neural network) were used to
investigate effects of biotic, abiotic, and anthropogenic
factors on demographic parameters and on their relation-
ships. Numbers of breeding pairs and of pairs with chicks
were affected by the same environmental factors, mainly
anthropogenic, which differed from those affecting the
number of fledged chicks per pair. Numbers of fledged
chicks per pair was not affected by colony size or by the
number of nests with chicks. The categorization of the
environmental variables into natural and anthropogenic, in
connection with demographic parameters, was relevant to
detect factors explaining variation in colony size and
breeding parameters. The SOM proved a relevant tool to
help determine actual dynamics in White Stork colonies,
and thus to support effective conservation decisions at a
regional scale.
Keywords White Stork Ciconia ciconia Algeria
Breeding performance Colony site Conservation
Zusammenfassung
Welche Umweltfaktoren regulieren Koloniegro
¨
ße und
Bruterfolg beim Weißstorch Ciconia ciconia?der
Einsatz von Selbstorganisier enden Karten
Untersucht wurden Unterschiede in Brutkoloniesta
¨
rke und
Bruterfolg bei Weißsto
¨
rchen Ciconia ciconia in Nordost-
algerien, in den Jahren von 2006–2008. Jede Kolonie wurde
anhand von zwo
¨
lf Umweltvariablen charakterisiert, welche
Auskunft u
¨
ber physische Umweltbedingungen, Land-
bedeckung und menschlichen Einfluss gaben, sowie anhand
von drei demografischen Parametern: der Anzahl der
Brutpaare, der Anzahl von Paaren mit Ku
¨
ken und der An-
zahl flu
¨
gger Junge pro Paar. Es wurden Generalisierte
Lineare Gemischte Modelle und der Selbstorganisierende
Karten-Algorithmus (Self-Organising Map, SOM, ein neu-
ronales Netz) angewendet, um die Wirkung biotischer,
abiotischer und anthropogener Faktoren auf die demogra-
fischen Parameter und die Beziehungen zwisch en diesen zu
untersuchen. Die Anzahl der Brutpaare und die der Paare
mit Ku
¨
ken wurden von denselben (hauptsa
¨
chlich anthrop-
ogenen) Umweltfaktoren beeinflusst. Dagegen wurde die
Communicated by P. H. Becker.
A. Si Bachir N. Djeddou
Department of Natural and Life Sciences, Faculty of Sciences,
University of El Hadj Lakhdar, Batna 05000, Algeria
H. Chenchouni
Department of Natural and Life Sciences, Faculty of Exact
Sciences and Natural and Life Sciences, University of Tebessa,
12002 Tebessa, Algeria
C. Barbraud (&)
Centre d’Etudes Biologiques de Chize
´
, CNRS UPR, 1934,
79360 Villiers-en-Bois, France
e-mail: barbraud@cebc.cnrs.fr
R. Ce
´
re
´
ghino F. Santoul
Laboratoire d’Ecologie Fonctionnelle et Environnement, EcoLab
UMR5245, Universite
´
Paul Sabatier, Ba
ˆ
timent 4R3-b2,
118 Route de Narbonne, 31062 Toulouse cedex 9, France
DOI 10.1007/s10336-012-0915-2

Anzahl flu
¨
gger Ku
¨
ken pro Paar von anderen Faktoren bes-
timmt: Weder die Koloniegro
¨
ße noch die Anzahl von Ne-
stern mit Ku
¨
ken hatten hier einen Einfluss. Die Einteilung
der Umweltvariablen in natu
¨
rliche und anthropogen bed-
ingte half in Verbindung mit demografischen Parametern
dabei, die Faktoren zu identifizieren, welche die Variation in
Koloniegro
¨
ße und den Brutparametern erkla
¨
ren. Die SOM-
Methode erwies sich als geeignetes Werkzeug zur Bes-
chreibung der tatsa
¨
chlichen Dynamik in Weißstorch-Kolo-
nien und stellt somit eine Hilfe bei der Festlegung effekt iver
Schutzmaßnahmen auf regionaler Ebene dar.
Introduction
Many studies have investigated biological and socio-eco-
nomic factors affecting threatened species in order to
understand the current biodiversity crisis (Scott et al.
1995). In birds, studies on habitat selection are of growing
importanc
e for conservation policy and planning because
they deal with quantitative information affecting the
dynamics of bird popu lations (Caughley
1994). Environ-
mental conditions are significa nt determinants in breeding
habitats, and may influence the breeding success of birds
and contribute to the variability of breeding populations
(Lack
1968). The determination of the factors (natural or
anthropogenic) affecting breeding success is the main
target of many bird conservation studies, since breeding
success can often be more easily managed than other
demographic parameters (Pedrini and Sergio
2002;
Gil-Sa
´
nchez et al.
2004; Manning et al. 2004).
Strictly or usually colonial bird species exhi bit wide
variation in colony size, with the smallest and largest
colonies within a species often varying by several orders of
magnitude. Numerous studies used natural variation in
colony size to measure fitness consequences of breeding
with different numbers of conspecifics (van Vessem and
Draulans
1986; Møller 1987; Brown and Brown 2001). In
addition, environmental factors or ecological situations
surrounding breeding sites of birds have critical impacts on
breeding success in either direct or indirect manners
(Burger and Shisler
1980; Cody 1985; Yorio et al. 1995).
In its breeding range, the White Stork (Ciconia ciconia)
nests either solitarily or colonially (Cramp and Simmons
1977). Altho ugh several studies investigated the factors
affecting White Stor k colony size and fitness parameters,
such as breeding success, independently (van Vessem and
Draulans
1986; Carrascal et al. 1993; Barbraud et al. 1999;
Moritzi et al.
2001; Jovani and Tella 2004; Tryjanowski
et al. 2005a, 2005b; Denac 2006), variations in colony size
and fitness may be due to different environmental factors,
and few studies have aimed at disentangling these fac-
tors. In fact, the effect of one environmental factor
(e.g., ambient temperature) may become evident, some-
times with lagged effects, only when other environmental
factors (e.g., food availability) affecting reproduction are
taken into account (Tryjanowski and Sparks
2008).
Therefore, the aim of this paper was to investigate the
main environmental factors affecting the distribution and
size of breeding colonies and breeding parameters of the
White Stork in an ecotone area located between the arid
and semi-arid bioclimatic stages. Most demographic stud-
ies on this species have been conducted in temperate areas,
mainly in Europe, where environmental conditions and life
history traits (e.g., clutch size, colonia l or solitary nesting)
differ from those encountered in northern Africa. This
species is of high conservation interest and its populations
have experienced considerable changes during the last
decades (Thomsen and Ho
¨
tker
2006). Our approach is
based on artificial neural network analyses that enhance our
ability to determine the actual dynamics in colony sizes
and breeding performance, and to investigate how these
demographic parameters are associated to broad-type nat-
ural as well as anthropogenic inf ormation.
Methods
Study area
The study was conducted in the Wilaya (departme nt) of
Batna, north-east Algeria, in an area of 12,192 km
2
located
between 6° and 7°E and 35° and 36°N (Fig. 1). The general
climate is typically Mediterranean with a continental influ-
ence (semi-arid area with cool winters), but ranges from the
arid to the humid category according to Emberger’s (1955)
classification. This wilaya is characterized by predominance
of high montane vegetation forests including tree species
such as Holm Oak (Quercus ilex L.), Atlas Cedar (Cedrus
atlantica M.), and Aleppo Pine (Pinus halepensis Miller.).
Plains are mostly used for cereal crops (mainly Durum
Wheat Triticum durum L. and Barley Hordeum vulg are L.)
and livestock. Livestock mainly includes extensive sheep
grazing and intensive poultry farming.
Survey method
Colonies of White Storks were censused during 3 years
(2006–2008) from early January to early July. We defined a
colony of storks as a breeding site with at least two nests
built on the same suppor t or on two supports separated by a
few meter s (\10 m). Based on dates of first hatched eggs
(2006: March 10; 2007: March 24; 2008: March 20), col-
onies censuses were carried out from May 20 to June 8
2006, from June 2 to July 2 2007 and from June 14 to 30
2008, in order to ensure that when the counts were made no
chick had already fledged. These dates were dictated

according to arrival dates of White Storks on one hand and
dates of the first hatched chick on the other hand. During
the survey period, the color of chicks’ beak and legs was
still blac k, thereby facilitating their detection in the nest
without confusion with the parents. According to Schu
¨
z
(
1936), Arnhem (1980), and Whitfield and Walker (1999),
at 6 weeks the black feathers on the wings appear, and in
the seventh week standing is regular and the chicks per-
form wing beats that prepares the muscles to fly. After the
ninth or tenth week, young chicks perform their first flight.
Censuses were carried out in all admini strative units of
the wilaya of Batna with assistance from the local staff of
the Forests Conservation Direction, who dir ected us
towards nesting sites of storks. Chick counts were often
made during the morning when chicks are fed more fre-
quently and are upright in the nest facilitat ing their count.
The number of chicks was estimated by eye or with
binoculars.
For each colony, the following parameters were
recorded:
(1) Site descripti on: name of the site, exact location
(longitude, latitude), census dates.
(2) The number of bree ding pairs (HPa), defined as a
male and female holding a nest with or without
chicks.
(3) The number of pairs with chicks (HPm), defined as a
male and female holding a nest with chicks, the
presence of chicks indicates the presence of a
breeding pair with chicks.
(4) The number of fledged chicks per nest (JZG). Fledged
chicks were defined as nestlings older than 7 weeks
which are still on the nest and about to fledge. At this
age, chicks are supposed to survive until fledging
since there is no or very slight mortality between the
census period and their fledging (Djerdali et al.
2008b). In computation, JZG was entered as the
average number of fledged chicks per breeding pair in
the colony.
Environmental variables
For each colony site we collected the following environ-
mental variables:
(1) Altitude in meters above sea level measured by an
altimeter (±1 m).
(2) Annual precipitation (mm).
(3) Cumulated precipitation (mm) recorded during
November, December, and January (winter rainfall)
corresponding to the pre-breeding period.
Fig. 1 The wilaya (department) of Batna, Algeria, with locations of the 62 colonies and densities of breeding pairs of White Storks (Ciconia
ciconia) per colony (census 2008). Numbers refer to colony codes

Citations
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Journal ArticleDOI
TL;DR: It is suggested that regardless of the climate or landscape, White Storks ensure a constant food intake, despite prey biomass fluctuations, by adapting their diet.
Abstract: Assessing diet composition of White Storks (Ciconia ciconia) breeding under North African conditions provides key information to understanding its trophic niche for conservation purpose. Since, climate controls productivities of foraging habitats and thus food availability for predators, this study examines how Storks’ diet parameters varied following a climate gradient along with rural-to-urban landscapes in north-eastern Algeria. Feeding strategies to cope with severe conditions were discussed in light of climate aridity and urbanization and how these influence reproduction, population dynamics and distribution. While invertebrate prey accounted for 94 % of ingested individuals, the biomass intake was dominated by chicken remains scavenged from rubbish dumps (67 %) and small mammals (14 %). Generalized linear models revealed that prey numbers varied significantly between climatic regions and landscapes types, but no significant differences were observed for other dietary parameters, including prey biomass. The study showed high dietary similarity between study climates and landscapes, mainly among rural and urban colonies located in semi-arid and sub-humid areas, which differed from those in suburban and arid climate. Rarefaction and extrapolation curves indicated that prey species richness in White Stork diets was expected to be higher in urban colonies located in sub-humid climate. Despite low prey species diversity in arid regions, the White Stork demonstrates a broad trophic niche, which could be due to supplementary feeding from human refuse. This study suggests that regardless of the climate or landscape, White Storks ensure a constant food intake, despite prey biomass fluctuations, by adapting their diet. Foraging in diverse habitats, including trash dumps, ensures a sufficiently balanced diet to meet nutritional requirements.

21 citations


Cites background or methods from "Using self-organizing maps to inves..."

  • ...Studies have investigated the influence of climate factors and variability in food availability at foraging/breeding habitats on reproductive patterns (Tortosa et al. 2003; Tryjanowski et al. 2005a; Denac 2006; Djerdali et al. 2008; Kosicki 2012; Si Bachir et al. 2013)....

    [...]

  • ...The diet of nesting pairs of White Storks in rural and urban areas of Batna (north-eastern Algeria), where the bulk of the White Stork population lives (Si Bachir et al. 2013), was studied using pellet analysis....

    [...]

  • ...Some substantial colonies also exist under hot-arid climatic conditions (Si Bachir et al. 2013)....

    [...]

  • ...The climate along with landscape type and structure, affects the productivity and breeding numbers of birds, through changes in water availability and agricultural conditions (Tryjanowski et al. 2005a, b; Ramo et al. 2013; Si Bachir et al. 2013)....

    [...]

  • ...In addition, Si Bachir et al. (2013) reported that levels of urbanization affected the breeding success and population densities of the species....

    [...]


Journal ArticleDOI
TL;DR: Results suggest that White Stork breeding success was also affected by natural food resources, since bigger colonies may deplete natural prey sooner, which is more evident in dry years.
Abstract: In the present study, we evaluated the effect of distance to food from rubbish dumps and colony size on White Stork breeding success. Waste from poultry farms is expanding in the study area and is commonly used by the White Stork as a new food resource, which may explain the increase in the number of breeding Storks in the region. The study was carried out at 24 sites, including 88 different colonies of White Stork in northern Algeria, Setif (36°09′N, 05°26′E; 900 m.a.s.l.); over a 4-year period (2002–2005) with considerable variation in rainfall. Nests were monitored at different distances from 30 rubbish dumps emanating largely from chicken farms. Results of the General Linear Mixed Models (GLMM) showed that breeding success of White Stork was dependent upon distance to dumps, recording the highest values in nests close to these places with food supply. There was a highly significant interaction between the year and the distance to the rubbish dumps. That is, reproductive success was higher when there was extra food in all years except in 2002, which could be due to the very low rainfall during spring 2002. Also, we found a significant interaction between colony size and distance to a rubbish dump. Results suggest that White Stork breeding success was also affected by natural food resources, since bigger colonies may deplete natural prey sooner, which is more evident in dry years.

11 citations


Cites background from "Using self-organizing maps to inves..."

  • ...In contrast, Si Bachir et al. (2013), in a study on colony size and breeding success in the White Stork in north-east Algeria, reported higher breeding success in areas with high precipitation rates in slightly anthropogenic habitats than in those pairs breeding close to rubbish dumps, and they…...

    [...]


Journal ArticleDOI
TL;DR: The findings suggest that the White Stork performs a balance in order to satisfy its food requirements by compensating reciprocally between intake of prey numbers and their biomass regardless of the phenological stage of reproduction.
Abstract: Assessing feeding conditions and variations of diet composition over the breeding season is of great help in the understanding of the ecological niche of species. In meeting this aim, the White Sto...

10 citations


Journal ArticleDOI
TL;DR: Growth parameters of White Stork nestlings were estimated in eastern Algeria, in the southern part of the species’ range, to investigate the effects of nest occupation date, laying and hatching dates, clutch size, number of hatchlings, productivity, hatching order, and brood reduction on nestling growth patterns.
Abstract: Survival and reproduction of young can be affected by growth parameters. It is thus important to estimate intraspecific growth rate variability and environmental factors affecting growth to better understand the dynamics of populations and the potential impacts of environmental changes. Growth parameters of White Stork (Ciconia ciconia) nestlings were estimated in eastern Algeria, in the southern part of the species’ range. A total of 2,756 measurements of 65 nestlings from 18 nests were taken for body mass, and tarsus, wing and bill lengths. Individual growth data were used to investigate the effects of nest occupation date, laying and hatching dates, clutch size, number of hatchlings, productivity, hatching order, and brood reduction on nestling growth patterns. Body mass and bill length growth rates were lower in the studied population than in a more northerly White Stork population. This supports the hypothesis of a geographic variation in intraspecific growth parameters. Chicks from nests occupied early reached higher asymptotic body mass but tended to grow more slowly. However, chicks from late arriving birds compensated for the difference in body mass and wing length by higher growth rates. Wing length was significantly affected by asynchrony and hatching order. Last hatched chicks had larger asymptotic wing lengths, lower wing growth rates and longer growth periods. Wings of nestlings from highly asynchronous broods grew faster but took more time to attain the inflection point. Brood reduction had a negative effect on nestling bill length at hatching. Chicks from nests with little brood reduction had a longer bill at hatching than nestlings from nests with high brood reduction.

9 citations


Cites background from "Using self-organizing maps to inves..."

  • ...In Algeria, White Storks most often breed in colonies of an average 11 pairs, but up to 45 pairs (Si Bachir et al. 2012; Moali-Grine et al. 2013)....

    [...]

  • ...Fledged chicks were defined as nestlings older than 7 weeks which were still on the nest and about to fledge (Si Bachir et al. 2012)....

    [...]


Journal ArticleDOI
TL;DR: The number of laid White Stork eggs and the proportion of eggs that turned into fledglings in an agriculture-dominated region in Eastern Germany and the most frequent observed mortality cause, nest fights, revealed the relevance of intraspecific competition in the study population.
Abstract: Numerous studies have explored the relationship between environmental factors and White Stork Ciconia ciconia reproduction, mainly expressing breeding success as the number of fledglings. Nonetheless, one of the most critical life-history stages in birds falls between egg-laying and fledging, and identifying the factors causing offspring mortality during this period provides valuable knowledge. We quantified the number of laid White Stork eggs and the proportion of eggs that turned into fledglings in an agriculture-dominated region in Eastern Germany. Moreover, we identified the factors among land cover, weather and arrival dates, which influenced these two reproductive measures the most, and analysed the monitored mortality causes. On average, four eggs were laid per nest, and 57.8 % of the eggs turned into fledglings. The number of eggs laid was best explained by the negative effect of the arrival date of the second stork, while the percentage of eggs that turned into fledglings was more dependent on weather: most important parameters were mean temperature in the fifth and seventh weeks after the assumed breeding start (i.e. around the assumed hatching date), and the number of consecutive days with precipitation when nestlings are assumed to be approximately 3 weeks old. In an agricultural environment, weather effects that potentially disturb food availability might be more important than effects directly affecting the survival of White Stork offspring. The most frequent observed mortality cause, nest fights, furthermore revealed the relevance of intraspecific competition in the study population.

6 citations


Cites background from "Using self-organizing maps to inves..."

  • ...…density and the reproductive outcome have been found in some White Stork populations (Barbraud et al. 1999; Nowakowski 2003; Dziewiaty 2005; Denac 2006a; Sæther et al. 2006), but not in all (Grishchenko 2004; Tryjanowski et al. 2005; Vergara et al. 2006; Fulı́n et al. 2009; Si Bachir et al. 2013)....

    [...]


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Abstract: Conservation biology has two threads: the small-population paradigm which deals with the erect of smallness on the persistence of a population, and the declining-population paradigm which deals with the cause of smallness and its cure. The processes relevant to the small-population paradigm are amenable to theoretical examination because they generalize across species and are subsumed by an inclusive higher category: stochasticity. In contrast, the processes relevant to the declining-population paradigm are essentially humdrum, being not one but many. So far they have defied tight generalization and hence are of scant theoretical interest. The small-population paradigm has not yet contributed significantly to conserving endangered species in the wild because it treats an erect (smallness) as if it were a cause

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"Using self-organizing maps to inves..." refers background in this paper

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"Using self-organizing maps to inves..." refers background in this paper

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Frequently Asked Questions (1)
Q1. What contributions have the authors mentioned in the paper "Using self-organizing maps to investigate environmental factors regulating colony size and breeding success of the white stork (ciconia ciconia)" ?

The authors studied variations in the size of breeding colonies and in breeding performance of White Storks Ciconia ciconia in 2006–2008 in north-east Algeria.